Reversible cycle system



Nov. 2l, 1950Y Q E. CLANCY 2,530,681

REVERSIBLE CYCLE SYSTEM Filed Nov. 18, 1947 2 Sheets-Sheet l Cond/Mbna! Oags/oe Cona/enden Cona/@HSQM Nov. 21, 1950 G. E. cLANcY REVERSIBLE CYCLE SYSTEM 2 Sheets-Sheet 2 Filed Nov. 18, 1947 ENN Patented Nov. 2l, y1950 REVERSIBLE CYCLE SYSTEM Gilbert E. Clancy, Los Angeles, Calif., assigner to Drayer-Hanson, Incorporated, Los Angeles, Calif., a corporation of California Application November 18, 1947, Serial No. 786,608

17 Claims.

This invention relates to improvements in reversible cycle refrigeration systems of the type in which the system is shifted from its heating cycle to its cooling cycle by changing the refrigerant circuit, and in which the condensing and evaporating coils or passages used for the heating cycle are distinct from those used for the cooling cycle.

In previous systems of the type described, when the system is to be operated, say, on the heating cycle, valve means must be actuated so that the refrigerant flowing from the compressor to the receiver passes through the appropriate one of the two condensers, and additional valve means must be actuated so that the refrigerant owing from the receiver back to the compressor passes through the appropriate one of the two evaporators. When the system is to be shifted to the cooling cycle, bringing into action the other condenser and the other evaporator, both valve means must be shifted either simultaneously or by properly coordinated action. Moreover, in such systems check valves are usually required between the condensers and the receiver, to prevent back iiow of refrigerant into the condenser which is temporarily idle.

An important object of the present invention is the improvement of such refrigerant-switching systems by generally simplifying the refrigerant circuit, and in particular by reducing the Y number of switching valves required. This leads to a corresponding simplification of the switching operation itself, since theA problem of coordinating the various manipulations is minimized or entirely eliminated.

The improved refrigerant circuiting comprises alternative refrigerant circuits each of which includes a condenser and an evaporator. Refrigerant is directed by valve means, for example by a single three-way valve, from the compressor into one or other of the two circuits, and is returned directly from this circuit to the compressor. No additional valving is required, the single valve means being capable of performing the entire switching operation.

The invention has the further advantage of providing more effective use of the charge of refrigerant, since substantially all of the refrigerant in the system is in use both on the heating i cycle and on the cooling cycle.

Two separate condensers and two separate evaporators may be provided, one condenser and one evaporator being used on the heating cycle and the other condenser and evaporator on the cooling cycle. Or, for example, the refrigerant 2 I coils ofthe condenser used on one cycle and those of the evaporator used on the other cycle may be fabricated as a single unit, and have common thermal exchange surfaces or fins for thermal contact with a circulated fluid to be heated or cooled. Dual heat exchange units of that type are described fully and claimed in my Patent No. 2,47,304, issued on June 28, 1949. The present invention can be put into effect in a system which uses such dual units, or in a system which does not use them, and in which, for example, four structurally independent heat exchange units are used as the two condensers and the two evaporators.

A clear understanding of the present invention, and of its further objects and advantages. will be had from the following description of an illustrative preferred embodiment, which is to be read in connection with the accompanying draw- 20 ings, of which:

Fig. l is a schematic drawing of an illustrative form of reversible refrigeration system embodying the invention;

Fig. 2 is a schematic drawing showing the use of refrigerant subcooling in a system like that of Fig. 1;

Fig. 2a is a fragmentary schematic drawing, corresponding to a portion of Fig. 2, and showing an alternative arrangement; and Y Fig. 3 is a schematic drawing of a modified reversible refrigeration system, also embodying the invention.

Fig. 1 illustrates use of the invention in a reversible cycle system for heating and cooling air which is circulated from and to the conditioned space through conditioned air duct I0 by fan II, heat thus exchanged being removed from or rejected to some external medium, here shown a's an outside air stream which is circulated through outside air duct I2 by fan I3. Condenser 20 and evaporator 2l are located within conditioned air duct I0 in heat exchanging relation with the air stream therein, and condenser 23 and evaporator 22 are in heat exchanging relation with the stream of outside air within duct I2. The system as illustrated includes also two liquid refrigerant receivers 24 and 25; two expansion valves 26 and 21, which represent any suitable pressure reducing means between the high pressure and the low pressure portions of the respective circuits; switching valve 28; and refrigerant compressor 29, which is driven by any suitable means, such for example as motor 30.

Fluid connections are provided as indicated between the various elements of the refrigerant astucci system. Line 4o carries compressed refrigerant vapor from compressor 2S to switching valve 28, and is in effect the compressor outlet. Valve 28 is shown schematically as a conventional threeway valve by which line it can be connected selectively to one or other o lines '42 and 413. Any suitable means providing such selective connections can be used, such for example as a conventional T-coupling at the position of valve 28 and two separate valves, one in each of the lines 42 and 43 (compare Fig. 3).

From switching valve 2li two refrigerant circuits, a heating circuit and a cooling circuit, lead back to the inlet of compressor 2d, these two circuits being distinct from each other throughout their lengths, from the point at which they branch on" from compressor outlet il@ to the point at which they join at the compressor inlet, which in effect is line il. Reirigerant flows through one or other of these circuits, according to the position of switching valve 28.

The heating circuit includes line e2, condenser 26, line dil, receiver 2d, line expansion valve 2S, evaporator 22 and line The cooling circuit includes line 43, condenser 23, line d5, receiver 25, line til, expansion valve 2l, evaporator 2i and line @9. It will be noted that the only valves which are needed in this system are switching valve 28 and the two expansion valves 26 and 2l which are used alternatively. No check valves are required, although check valves or other additional means for controlling the rate or direction of refrigerant ow may loe provided at appropriate points in the system if desired.

When air in duct ll@ is to be heated, switching valve 2d is set in the position indicated in Fig. l, cutting line d@ E from line d3 and connecting it to line d2, so that compressed refrigerant is directed into the above described heating circuit (solid arrows). Compressed refrigerant vapor is then condensed in condenser 2d, giving up heat to the air t0 be conditioned, and is delivered as liquid to receiver 2d. Ezpansion valve 2G, which is controlled in any suitable manner, permits flow of refrigerant to evaporator 22 at such a rate as to maintain the system in. proper balance. Evaporation of liquid refrigerant in evaporator 22 gives up heat to the outside air Stream in duct l2. The resultant refrigerant vapor returns via line l to compressor inlet 5@ and is recirculated through the system by compressor 2Q.

When the system is operated thus on its heating cycle, the cooling circuit is cut off from the compressor outlet by switching valve 28 s0 that no vapor can enter the cooling circuit from conipressor 29; but the cooling circuit remains connected via line de to the outlet il of compreseor inlet, so that the pressure within the cooling circuit is maintained at substantially the suction pressure of the compressor. Since all parts of the idle cooling circuit are ordinarily at a higher temperature than, say, the working evaporator 22 of the heating circuit (which is colder than the relatively cold outside air) the vapor pressure of liquid refrigerant in the cooling circuit exceeds the suction pressure in line` 48 (which is necessarily less than the vapor pressure in the working evaporator). Therefore, any refrigerant which exists initially within this cooling circuit in the form of liquid, including that within receiver 25, is converted to vapor and is thus substantially wholly removed from the cooling circuit. Expansion valve 21 does not prevent the out-flow of refrigerant under'these conditions,

although it does limit the rate at which refrigersuperheat at the outlets of their respective evaporators, as is the usual practice, it will he seen that the valve in the idle circuit tends to remain open, since the degree of superheat gradually increases as the circuit becomes idle. That is because the pressure remains substantially equal to the compressor suction pressure, and the temperature tends to rise as the evaporator ceases operation and the adjacent condenser (in the other refrigerant circuit) comes into opereticn and becomes warm.' The expansion valve in the idle circuit therefore remains open, or even opens more widely, as the refrigerant liquid in that circuit is removed.

The system is switched to its cooling cycle by the single operation of setting valve 28 to disconnect line d@ from line l2 and connect it to line t3 and the cooling circuit (dashed arrows). Compressed refrigerant vapor is then condensed in condenser 23, giving up heat to the outside air stream in duct l2, and is delivered as a liquid to receiver 2e. The liquid then flows through expansion valve 2l, and is ree-evaporated in evaporator 2l, absorbing heat from the conditioned air stream and thus cooling that air. During operation of the cooling cycle, the heating circuit remains connected to the suction side of the compressor at lill, and the refrigerant within the heating circuit is therefore exhausted by the cornpresser, as has .iust been described for thev cooling circuit during the heating cycle. The idle evaporator 22 of the heating circuit, in the relatively warm outside air stream, is then ordina at a temperature higher than that of the act 1e cooling evaporator 2i in the cooled conditioned air stream, so that any liquid the heating circuit is vaporized and substantially wholly withdrawn.

Thus, whether the system is operated on its heating cycle or 0n its cooling cycle, the circuit which is not in use is substantially empty refrigerant, virtually the whole of the refrigerant charge being usefully employed in the active circult. When the system, after operation for a period on one cycle, is switched to the other cycle, the circuit which was previously active is gradually exhausted through compressor inlet Sil; and the circuit which was previously empty is gradually lled with refrigerant through compressor outlet dil and switching valve 28. ln practice only a few minutes are required after switching from one cycle to the other before the transfer of refrigerant between the two circuits is cornpleted and the system attains its new equilibrium.

Since the system is switched from one cycle to the other by operation of the single three-way switching valve 28, the switching operation is greatly simplified as compared with previous systems. Accordingly, there is a corresponding simplication in the control equipment which is necessary to provide automatic switching of the improved system in accordance with varying ternperature conditions or the like.

The use of refrigerant subccoling to increase the effective capacity of conventional refrigeration systems is well known. Fig. 2 illustrates a preferred arrangement of subcoolers for use with the improved system shown in Fig. 1. Two distinct subcoolers l2 and I3 are provided, connected respectively in the heating and cooling refrigerant circuits, preferably between the receivcooling coil 58 via line 41a and is returned to expansion valve 21 via line I'lb. During either the heating or cooling cycle, the subcooler which is not in use soon becomes substantially empty of' refrigerant, like the remainder of the idle re.

frigerant circuit. i The advantage to be obtained from a subcooler r During the cooling cycle, -liquid refrigerant from receiver 25 reaches subis greater the lower the temperature of the refrigerant liquid leaving it. It is therefore desirable to place the'subcooler coil in as cool a position as possible. It is also desirable, particularly' when the condenser is cooled by an air stream y (as in the present instance), to avoid placing the subcooler in that air stream in advance of the condenser, since the air reaching the condenser is then warmed in the subcooler, reducing the effectiveness of the condenser. A further consideration in the arrangement of a subcooler'in the air circuit is the provision of a satisfactory rate of air ow over the subcooler coils without the need of a special fan or other equipment.

'I'he novel manner of obtaining suitable air streams through the subcoolers, illustrated in Fig. 2, is advantageous in all the respects just mentioned, and greatly increases the utility of the system as a whole, particularly when the refrigerant circuits. are also arranged in accordance with the present invention. Subcooler 52 of the heating circuit is placed in the duct 54 through which fresh outside air is drawn by fan Ii into the main conditioned air duct I0. Duct 54 opens into that portion of duct Iii which lies `between fan H and condenser 20. The air pressure in that portion of duct It is appreciably below atmospheric pressure, due to the pressure drop of the air stream passing through the relatively restricted passages of condenser coll (and, in the present instance, of evaporator 2i). This low air pressure produces an effective flow of cool outside air through duct 54 and over subcooler 52, and this flow does not interfere with the normal flow of cooling air over condenser 28.

Similarly, subcooler 53 of the cooling circuit is placed in duct 55 which leads from the outside into that portion of outside air duct i2 which lies between fan I3 and condenser 23. Thus on the cooling cycle, a strong blast of outside air is drawn through the air passages of subcooler 53 by the main outside air fan I3. Dampers can be provided if desired in subcooler ducts 54 and 55, for the regulation of air ilow therein. However, I prefer to omit such dampers and to allow a uniform amount of fresh air to enter the conditioned space Via duct 5l whether that space is being heated or cooled.

It may be desirable to provide a subcooler in only one of the refrigerant circuits, thus increasing the heat exchanging capacity of the system when that circuit is operating. For example, if maximum capacity is required on the heating cycle but not on the cooling cycle, subcooler 53 and the outside air duct 55 in which it is placed may be omitted. The advantages described above will be obtained in connection with the arrangement of subcooler 52 and fresh air duct 54 with relation to fan il and condenser 20. In

fact this same type of arrangement is advantageous not only in reversible systems. but is also applicable to ordinary refrigeration sy'stems'which use an air stream to cool the condenser, or to reversed cycle systems for heating an air stream,

A modification of the arrangement of Fig. 2, such as that shown in Fig. 2a,- retains the advantages .iust described and has the additional advantage of increasing the capacity of the system when operating on its cooling cycle. In the arrangement of Fig. 2, it is substantially immaterial for the present discussion which of the two blast Vcoils 20 and 2| comes rst in the circulated air stream in duct i0. or indeed whether they are incorporated in a unitary structure. In Fig. 26 condenser 2li and evaporator 2i are preferably so arranged that the circulated air passes nrst through the condenser and then through the evaporator. Makeup air duct 54a opens into duct I0 between the condenser and evaporator, at a position which is downstream from condenser 2l (as is also true in Fig. 2) but upstream from evaporator 2l. With this arrangement what has been said in connection with Fig. 2 and with regard to the relationship of duct 54, condenser 20 and fan Ii still applies and the described advantages still obtain. The arrangement of Fig. 2a, however. has the advantage that on the cooling cycle, (when condenser 2i) and subcooler 52 are not operating) the relatively warm outdoor makeup air from duct 54a enters the circulated air stream in advance of evaporator 2i, increastive of some of the many diilerent types and combinations of heat exchanging devices which can be used with my invention. Compressed refrigerant vapor leaves compressor 29 via outlet line lila to the T-connection 56, from which two distinct refrigerant circuits, for heating and cooling respectively, lead back to compressor inlet line 50a. The heating circuit leads from T-connection 56 through control valve 51 to condenser 20a, receiver 24a, expansion valve 26a and evaporator 22a. The cooling circuit leads from T-connection 56 through control valve 58, condenser 23a, receiver 25a. expansion valve 21a' and evaporator Zia. In this system, the heating cycle is put into operation by opening control valve 51 and closing valve 58, and the cooling cycle by closing valve 5l and opening valve 58. No other control valves are required. Condenser 20a, by which the conditioned space 59 is heated, is not directly exposed to an air stream which enters this space, but gives up its heat to an auxiliary fluid, such as water, which is circulated by pump 60 through tank 6| enclosing condenser 20a and through radiator 62 which is located Within conditioned space 59. On the other hand, evaporator 21a, by which the conditioned space is cooled, is shown located within a duct G5 and exposed to a stream of air which is recirculated from the conditioned space by fan 66.

Evaporator 22a in the heating circuit and condenser 23a in the cooling circuit, which do not operate simultaneously. are in heatexchanging relation with a stream of water from any convenient source (not shown) which circulates in series over the coils of the -two heat exchanging units in tanks 61 and fl respectively. entering via line and leaving via line 1 I This water stream thus performs a similar function to that of the outside air stream in the system of Fig. 1. Alternatively, evaporator 22a might receive heat from any other suitable heat source, and condenser 23a might give up heat to any suitable medium.

The particular means for transferring heat to and from the various heat exchange units in the systems shown in Figs. 1 and 3 are illustrative of possible arrangements, but neither these nor other details of the above described embodiments of the invention are intended as limitations upon its scope.

I claim:

1. In a reversible refrigeration system, two lx1- dependent refrigerant circuits, each having a relatively high pressure portion including a refrigerant condenser, a relatively low pressure portion including a refrigerant evaporator, and each having a fluid connection between Sie two said portions including means adapted to limit the rate of refrigerant flow from the high pressure portion to the low pressure portion, and means including a refrigerant compressor for transferring refrigerant vapor from the low pressure portions of both refrigerant circuits selectively to the high pressure portion of either of the circuits, those portions of the two circuits lying between the respective condensers and evaporators being mutually distinct.

2. A reversible refrigeration system as defined in claim 1 and in which both said refrigerant circuits are continuously open for refrigerant flow from their respective high pressure portions via their low pressure portions to the said refrigerant compressor.

3. A reversible refrigeration system as defined in claim 1 and in which both said refrigerant circuits are continuously open for refrigerant flow in either direction between their respective high pressure and low pressure portions 4. A reversible refrigeration system adapted for selectively heating or cooling a space, and comprising refrigerant vapor compressing means having a refrigerant inlet and a. refrigerant outlet, two refrigerant circuits leading from said outlet to said inlet, each of said circuits including refrigerant condensing means, pressure reducing means and refrigerant evaporating means, means for transferring heat from the condensing means of one circuit to the said space and from the said space to the evaporating means 0f the other circuit, means for supplying heat to the evaporating means of the said one circuit and for removing heat from the condensing means of the other circuit, and means for limiting the flow of refrigerant from the compressor outlet selectively to either of the said circuits, the refrigerant y passages of the two said refrigerant circuits being mutually independent.

5. A reversible refrigeration system for rselectively heating or cooling a fluid, said system comprising :efrigerant vapor compressing means hav ing a refrigerant inlet and a refrigerant outlet,

heat exchanging relation with the condensing means of one circuit and with the evaporating means of the other circuit, means for bringing at least another fluid into heat exchanging relation Awith the evaporating means of the said one circuit and with the condensing means of the other circuit, and valve means between the compressing means and the two condensing means and adapted to direct the flow of refrigerant from the compressing means selectively into either of the two circuits, the refrigerant passages of the two said parallel circuits being mutually distinct.

6. A reversible refrigeration system as defined ing" claim 5 and in which both said circuits are open for refrigerant flow from their respective condensing means to the said compressor inlet, subject only to the said pressure reducing means of each circuit, and regardless of the condition of the said valve means.

7. A reversible refrigeration system as defined in claim 5 and in which both said circuits are open for refrigerant flow in either direction between their respective condensing means and their respective evaporating means, subject only to the said pressure reducing means of each circuit, and regardless of the condition of the said valve means.

8. A reversible refrigeration system for selectively heating or cooling a fluid, said system comprising refrigerant vapor compressing means having a refrigerant inlet and a refrigerant outlet, two parallel circuits for refrigerant flow from the said outlet to the said inlet, each of said circuits including refrigerant condensing means, pressure reducing means and refrigerant evaporating means, means for bringing the said fluid into heat exchanging relation with the condensing means of one circuit and with the evaporating means of the other circuit, means for supplying heat to the evaporating means of the said one circuit and for removing heat from the condensq ing means of the other circuit, and valve means between the compressing means and the two condensing means and adapted to direct the flow of refrigerant from the compressor selectively into one of the two circuits, the refrigerant passages of the two said parallel circuits being mutually distinct.

9. A reversible refrigeration system as defined in claim 8 and in which each of the said circuits includes also a receiver for liquid refrigerant, located between the condensing means and the pressure reducing means.

l0. In a reversible refrigeration system which is adapted for transferring heat in either direction between a first and a second fluid and which comprises first and second refrigerant condensing means, first and second refrigerant evaporating means, means for flowing the first said fluid in heat exchanging relation with the two said first means, refrigerant vapor compressing means, each of the4 said means having a refrigerant inlet and a refrigerant outlet, means for flowing the second fluid in heat exchanging relation with the two said second means, fluid connections from the outlets of the two evaporating means to the inlet ofthe compressingmeans,fluid connections from the outlet of the compressing means to the inlets of the two condensing means, and valve means in,

the last mentioned fluid connections adapted to direct refrigerant from the compressor selective ly to one or other of the two condensing means; the improvement which comprises one fluid connection between the outlet of the l'lrst condensing means and the inlet of the second evaporating means, and a second fluid connection between v ceiver and a pressure reducing means.

13. A reversi-ble refrigeration system as defined in claim 12 and in which at least one of the two last mentioned fluid connections includes heat exchange means interposed between the receiver and the pressure reducing means and adapted to remove heat from refrigerant fluid passing therethrough.

14. In a reverse cycle refrigeration system which is adapted for heating a space and which includes an air passage communicating at both ends with the space, a fan in the air passage adapted to circulate air through the passage from the space, refrigerant vapor compressing means having an inlet and an outlet, a refrigerant circuit leading from the outlet to the inlet and including refrigerant condensing means arranged in the air passage ahead of the fan, refrigerant pressure reducing means and refrigerant evaporating means, and means for removing heat from the refrigerant evaporating means:

.the improvement which comprises a second air passage communicating between the outside air and that portion of the first said air passage which lies between the condensing means and the fan, a refrigerant passage in heat exchanging relation with air in the second air passage. and means for conducting refrigerant from the condensing means through the refrigerant passage to the pressure reducing means.

i5. In a reversible refrigeration system which is adapted for selectively heating or cooling a space andv which comprises a first air passage communicating yat both ends with the space, a fan in the said passage adapted to circulate air from and to the space through the said 'passage, a refrigerant condenser and a refrigerant evaporator arranged in the said passage. at least the condenser being located ahead of the fanl in the passage air stream. means.adavfed fn circulate fluid refrigerant selectively as vapor to the condenser and as liquid to the evaporator; the improvement which comprises a second air passage communicating between the outside air and the first said air passage, a refrigerant coil arranged in the second air passage and adapted to receive refrigerant liquid condensed in the condenser. the second air passage commmunicating with the nrst passage at a point which lies between the condenser 'and the fan.

16. A reversible cycle refrigeration system as described in claim 15 and in which the evaporator is located in the first air passage between thefan and the point of communication between the two air passages.

Q 17. In a reversible refrigeration system which is adapted for selectively heating or cooling a space and which comprises a rst passage comfmunicating at both ends with thespace, a fan in the said passage adapted to circulate air from the space through the said passage, a second passage communicating at both ends with the outside air, a fan in the second passage adapt-4 ed to circulate outside air through the second passage, a first refrigerant condenser and a first refrigerant evaporator arranged in the first air passage, at least the condenser being located ahead of the fan in the air stream, a second refrigerant condenser and a second refrigerant evaporator arranged in the second passage, at least the condenser being located ahead of the fan in the air stream, first and second refrigerant pressure reducing means, and means, including a refrigerant compressor, for circulating refrigerant selectively through a first refrigerant circuit which includes successively the first condenser, the first pressure reducing means and the second evaporator, or through a second refrigerant circuit which includes successively the second condenser, the second pressure reducing means and the first evaporator: the improvement which comprises a third passage communicatingbetween the outside air rand that portion of the nrst passage which lies between the fan and the said first condenser, a fourth passage communicating between the outside air and that portion of the second passage which lies between the fan and the said second condenser, a refrigerant coil connected in the first said refrigerant circuit between the condenser and the pressure reducing means and arranged in heat exchanging relation with air inthe third said passage, and a refrigerant coll connected in the second said refrigerant circuit between the condenser and the pressure reducing means and arranged in heat exchanging relation with air in the fourth said passage.

. GILBERT E. CLANCY.

REFERENCES crrnnA The following references are of record in the file of this patent:

2,474,304 Clancy June 28, 1949 

